a) Field of the Invention
This invention relates to new and novel compositions of matter classified in the art of chemistry as oxalic acid peroxide compositions of Structure A, ##STR2## The definitions of R, R.sup.1, R.sup.2, R.sup.3, Z, and n are given in the SUMMARY OF THE INVENTION!
e.g., allyl 3-t-butylperoxy-1,3-dimethylbutyl oxalate, and use of the novel oxalic acid peroxide compositions of Structure A. The compositions possess inherent applied use characteristics making them suitable for use as initiators a) for polymerizing ethylenically unsaturated monomers, b) for curing of unsaturated polyester resins, c) for curing of elastomers, d) for crosslinking of polyolefins, e) for modifying polyolefins, f) for grafting of vinyl monomers onto polymer backbones and g) for compatibilizing blends of two or more incompatible polymers.
There is a need in the polymer industry for efficient, free-radical crosslinking agents for olefin polymers which give longer scorch times and yet result in faster crosslinking rates. Because of its low melt flow high density polyethylene (HDPE) must be compounded with peroxides at temperatures where the scorch time is relatively short. If the scorch time is too short, premature crosslinking of HDPE occurs during the peroxide compounding step. This is highly undesirable. In the crosslinking of HDPE the peroxide that is predominantly used for crosslinking is 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne (Lupersol 130; manufactured by ELF ATOCHEM North America, Inc.). Of all the commercial organic peroxides, Lupersol 130 has the highest 10 hour half-life temperature (131.degree. C.). The 10 hour half-life temperature of an initiator is defined as the temperature at which 50% of the initiator will decompose in 10 hours. Generally, the higher the 10 hour half-life temperature the longer the scorch time at a given temperature.
Although Lupersol 130 gives adequate scorch times when compounded into HDPE, polymer producers complain of the noxious decomposition products that Lupersol 130 produces during crosslinking of polyethylene. The noxious decomposition products are thought to be derived from the carbon-carbon triple bond in Lupersol 130 since a similar peroxide that lacks the carbon-carbon triple bond, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, does not produce noxious decomposition products. An efficient polyethylene crosslinking agent which yields lengthened scorch times and produces less noxious decomposition products is needed by the polyethylene crosslinking industry.
A novel oxalic acid peroxide composition of the instant invention, allyl 3-t-butylperoxy-1,3-dimethylbutyl oxalate, satisfied most of these crosslinking criteria and was found to be a more effective HDPE crosslinking agent than was Lupersol 130. At 385.degree. F. in HDPE, allyl 3-t-butylperoxy-1,3-dimethylbutyl oxalate was found to be significantly more efficient than Lupersol 130 on an equivalent basis and was found to crosslink HDPE much more rapidly than Lupersol 130. Hence, it was superior to Lupersol 130 for crosslinking of HDPE. Because allyl 3-t-butylperoxy-1,3-dimethylbutyl oxalate contains no carbon-carbon triple bond, generation of noxious decomposition products during crosslinking of polyethylene is unlikely.
In recent years most of the new polymeric materials that have been commercialized are polymeric blends and alloys composed of two or more different polymers. The reasons for this trend to commercial development of polymer blends and alloys include the short time required for development and commercialization of these materials, the relatively low cost involved in carrying out the R&D effort needed to develop these materials compared to development of entirely new polymers from monomers, and the ability to develop polymeric blends and alloys that are "tailor made" to meet end use property specifications, hence, they are neither over-engineered nor under-engineered, but just right.
The polymer property improvements achieved by blending include:
Better processability PA1 Impact strength enhancement PA1 Improved flame retardance PA1 Improved barrier properties PA1 Improved tensile properties PA1 Improved adhesion PA1 Improved melt flow PA1 Enhanced heat distortion temperature (HDT) PA1 Enhanced heat resistance PA1 Improved stiffness PA1 Improved chemical resistance PA1 Improved ultraviolet light stability PA1 x is 0 or 1, R.sup.6 is a substituted or unsubstituted alkyl radical of 1 to 18 carbons, substituents being one or more alkyl radicals of 1 to 6 carbons, t-alkylperoxy radicals of 4 to 8 carbons, alkoxy radicals of 1 to 6 carbons, aryloxy radicals of 6 to 10 carbons, hydroxy, chloro, bromo or cyano, and a substituted or unsubstituted cycloalkyl radical of 5 to 12 carbons optionally having an oxygen atom or a nitrogen atom in the cycloalkane ring, with substituents being one or more lower alkyl radicals of 1 to 4 carbons, and, PA1 R.sup.7 is selected from a substituted or unsubstituted alkylene diradical of 2 to 3 carbons, substituents being one or more lower alkyl radicals of 1 to 4 carbons, and substituted or unsubstituted 1,2-, 1,3- and 1,4-phenylene diradicals, substituents being one or more lower alkyl radicals of 1 to 4 carbons, chloro, bromo, nitro or carboxy, and, PA1 R.sup.8 is a lower alkyl radical of 1 to 4 carbons, and, additionally, the two R.sup.8 radicals may be concatenated to form an alkylene diradical of 4 to 5 carbons, and, PA1 R.sup.9 is a lower alkyl radical of 1 to 4 carbons, and, PA1 R.sup.10, R.sup.11, and R.sup.12 can be the same or different and are selected from the group consisting of hydrogen, alkyl radicals of 1 to 8 carbons, aryl radicals of 6 to 10 carbons, alkoxy radicals of 1 to 8 carbons and aryloxy radicals of 6 to 10 carbons, and, PA1 R.sup.1 and R.sup.2 are lower alkyl radicals of 1 to 4 carbons, and, when R is selected from a t-alkyl radical of 4 to 12 carbons R.sup.2 can additionally be a t-alkylperoxy radical of 4 to 12 carbons, R.sup.3 is selected from the group consisting of a substituted or unsubstituted alkylene diradical of 2 to 4 carbons and a substituted or unsubstituted alkynylene diradical of 2 to 4 carbons, substituents being one or more lower alkyl radicals of 1 to 4 carbons, and, PA1 when n is 1, Z is selected from the group consisting of OR.sup.13, NR.sup.13 R.sup.14, OO--R, Cl and Br, where R.sup.13 and R.sup.14 are the same or different and are selected from the group consisting of hydrogen, substituted or unsubstituted alkyl radicals of 1 to 18 carbons, substituents being one or more alkyl radicals of 1 to 6 carbons, alkoxy radicals of 1 to 6 carbons, aryloxy radicals of 6 to 10 carbons, acryoyloxy radicals, methacryloyloxy radicals, chloro, bromo and cyano, substituted or unsubstituted alkenyl radicals of 3 to 12 carbons, substituents being one or more lower alkyl radicals of 1 to 4 carbons, substituted or unsubstituted aryl radicals of 6 to 10 carbons, substituents being one or more alkyl radicals of 1 to 6 carbons, alkoxy radicals of 1 to 6 carbons, aryloxy radicals of 6 to 10 carbons, chloro, bromo and cyano, substituted or unsubstituted aralkyl radicals of 7 to 11 carbons, substituents being one or more alkyl radicals of 1 to 6 carbons, alkoxy radicals of 1 to 6 carbons, aryloxy radicals of 6 to 10 carbons, chloro, bromo and cyano, and substituted or unsubstituted cycloalkyl radicals of 5 to 12 carbons optionally having an oxygen atom or a nitrogen atom in the cycloalkane ring, with substituents being one or more lower alkyl radicals of 1 to 4 carbons, and Z is also selected from structure (g), ##STR10## R.sup.15 is selected from the definitions of R, with the proviso that R and R.sup.15 are not the same, and PA1 when n is 2, Z is selected from the group consisting of structures (h), (i), and (j), EQU --O--R.sup.16 --O-- (h), --NR.sup.13 --R.sup.16 --NR.sup.14 -- (i), --NR.sup.13 --R.sup.16 --O-- (j), PA1 R.sup.16 is selected from the group consisting of substituted or unsubstituted alkylene diradicals of 2 to 10 carbons, substituents being one or more lower alkyl radicals of 1 to 4 carbons, and arylene diradicals of 6 to 14 carbons, substituents being one or more lower alkyl radicals of 1 to 4 carbons. PA1 a. curing of unsaturated polyester resin compositions, PA1 b. polymerizing ethylenically unsaturated monomers (such as styrene, ethylene) compositions, PA1 c. crosslinking of olefin thermoplastic polymer compositions, PA1 d. curing of elastomer compositions, PA1 e. modifying polyolefin compositions, PA1 f. grafting of ethylenically unsaturated monomer substrates onto olefin homo- and copolymer substrates, and, PA1 g. compatibilizing blends of two or more normally incompatible polymer substrates;
The major problem encountered in developing new blends and alloys is the inherent incompatibility or immiscibility of almost all mixtures of two or more polymers. The consequence of incompatibility of polymeric blends and alloys is that they are unstable and, with sufficient time and temperature, form separate phases, thus physical properties of the polymeric blends and alloys suffer. Generally, resin compounders have found that block and graft copolymers having polymeric segments that are compatible with the individual polymer components of blends and alloys enable formation of blends and alloys having enhanced phase stabilities and physical properties.
Low cost blends and alloys are commercially produced from two or more addition polymers such as blends involving low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and polypropylene (PP). The compatibility of these low cost blends can be improved by crosslinking with peroxides or by use of compatibilizing block or graft copolymers as mentioned above.
An important use of peroxides such as the novel oxalic acid peroxide compositions of Structure A is their utility in preparing graft copolymers useful for compatibilizing polymeric blends and alloys. The novel oxalic acid peroxide compositions of Structure A of the instant invention, are effective in the preparation of graft copolymer compositions. Such graft copolymers have utility in compatibilizing polymer blends and alloys.
b) Description of the Prior Art
U.S. Pat. No. 3,236,872 (Feb. 22, 1966, to Laporte Chemical, Ltd.) discloses hydroxy-peroxides of the structure: ##STR3## (wherein R-- is a H--, an acyl, an aroyl or alkyl group, especially the t-butyl group, t-amyl or the hexylene glycol residue; R'-- is an H-- or an acyl, aroyl or alkyl group.)
U.S. Pat. No. 4,525,308 (Jun. 25, 1985, to Pennwalt Corp.) and U.S. Pat. No. 4,634,753 (Jan. 6, 1987, to Pennwalt Corp.) disclose hydroxy-peroxyesters (above structure where R'-- is H-- and R-- is an acyl group) having 10 hour half-life temperatures below about 75.degree. C.
U.S. Pat. No. 3,853,957 (Dec. 10, 1974, to Pennwalt Corp.) discloses diperoxyketals and ketone peroxides containing hydroxy and acyloxy groups.
U.S. Pat. No. 3,846,396 (Nov. 5, 1974, to Pennwalt Corp.) and U.S. Pat. No. 3,725,455 (Apr. 3, 1973, to Pennwalt Corp.) disclose coupled peroxides of the structure, EQU R--W--R'
where R-- and R'-- are identical and are peroxide containing alkoxy radicals having at least two carbons and an oxygen atom between the peroxide groups (--OO--) of the R-- and R'-- groups and --W-- is a diradical selected from the class consisting of several diradical structures including, ##STR4##
U.S. Pat. No. 3,846,396 and U.S. Pat. No. 3,725,455 are close art when --W-- is --C(O)--C(O)--. However, the structures of this art do not anticipate the compositions of Structure A.
U.S. Pat. No. 3,706,818 (Dec. 19, 1972, to Pennwalt Corp.) and U.S. Pat. No. 3,839,390 (Oct. 1, 1974, to Pennwalt Corp.) disclose sequential polyperoxides possessing peroxide moieties of differing structures and activities in the same molecule. The structures of this art do not anticipate the sequential polyperoxides of Structure A.
U.S. Pat. No. 3,671,651 (Jun. 20, 1972, to Pennwalt Corp.) discloses peroxy compounds containing haloformate (e.g., chloroformate and carbonyl chloride) groups. Some of the novel oxalic acid peroxide compositions of Structure A contain the chlorooxalate group, --O--C(O)--C(O)--Cl, which is different, easier to incorporate onto a hydroxy-peroxy compound than is a haloformate group (especially when the hydroxyl group is a secondary or a tertiary hydroxyl group) and which is more reactive in subsequent reactions than a haloformate (i.e., with a secondary or a tertiary hydroxyl compound and/or in the absence of a base). Hence, the novel oxalic acid peroxide compositions of Structure A advance the art over that disclosed in U.S. Pat. No. 3,671,651.
U.S. Pat. No. 3,660,468 (May 2, 1972, to Pennwalt Corp.) discloses peroxyester compounds containing carboxy groups. The carboxy compounds of Structure A contain the --O--C(O)--C(O)--OH group which is significantly different than the carboxy group of the carboxy-containing peroxyesters of U.S. Pat. No. 3,660,468. In addition, the carboxy compositions of Structure A are more easily produced than are the carboxy-containing peroxyesters of U.S. Pat. No. 3,660,468.
c) Definitions
In the instant invention, t-cycloalkyl refers to the monoradical structure, ##STR5## where t is 0 to 2 and R.sup.x is a lower alkyl radical of 1 to 4 carbons, t-alkynyl is the monoradical structure, ##STR6## where R.sup.y is hydrogen or a lower alkyl radical of 1 to 4 carbons, and t-aralkyl is the monoradical structure, ##STR7## where R.sup.z is an aryl radical of 6 to 10 carbons.
When any generalized functional group or index, such as R, R.sup.1, R.sup.2, x, n, etc., appears more than once in a general formula or structure, the meaning of each is independent of one another.